The new JTV interface may be electrically the same as the old Variax USB interface but it is a small black thing about 1/4 the size of the original and it has a USB dongle hanging out one side. I have not tried this with my old Variax but I am sure it will work. Neither one powers the Variax through USB. I suspect that the reason is that the Variax violates the USB spec on 5V current. (too high)

and I used batteries to power the Variax. The light on the interface did not change from red to green on the Variax side. The one I have is a clear plastic top unit with usb on one side and the Variax cable on the other.

Yes my new JTV69S came with a different USB interface. 1/3 the size black plastic with a dongle cord for the USB side. It works the same and I think it is interchangeable with the old unit shown here. I bought workbench years ago for my 500 and it came with the clear plastic interface.